Phantom telephone system.



PATENTBD DEC. 11, 1906.

T. P.-J.0RDAN.- PHANTOM TELEPHONE SYSTEM. APPLIOATIONIILED 0012a, 1904.RENEWED D120. 20. 1005.

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No- 888,028. v PATENTED DEC. 11, 1906.

' T. P. JORDAN.

PHANTOM TELEPHONE SYSTEM.

APPLICATION FILED 00313.3, 1904. RENEWED DEC. 20. 1905.

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i MED/2 g I War/7y PATENTED 1130.11, 1906. T. P.. JORDAN.

PHANTOM TELEPHONBSYSTEM. APPLICATION FILED 0013, 1904. RENEWED D110. 20.1905.

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THOMAS P. JORDAN, OF DALLAS, TEXAS, ASSIGNOR TO E. H. CARY, OF

DALLAS, TEXAS.

PHANTOM TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Dec. 11, 1906.

Application filed October 3, 1904. Renewed December 20. 1905. Serial No292.588.

To a, whom it may concern:

Be it known that I, THOMAS I. JORDAN, a citizen of the United States,residing at Dallas, Texas, have invented a Phantom Telephone System, ofwhich the following is a specification.

This invention relates to a system of transmission of electrical energy,and more particularly to telephones; and the object is to roducetelephone-circuits more economica ly than can be done with any knownsystem of telephones by providing devices by which superposed or phantomcircuits may be established by which a number of conversations can becarried on simultaneously on the same circuits without interference andby which devices a point of zero-potential can be detected orestablished or shifted.

In multiplex telephony many attempts have been made to carry onsimultaneously a number of conversations by establishing supplrposed or)hantom circuits.

own all suc attempts have been failures.

In combined telephone and telegraph lines a system in ordinary usecomprises an allmetallic telephone-circuit provided at each end with theusual transmitting and receiv ing instruments, and a telegraph-circuitis established byconnecting a short line at each end of the telehone-circuit at a point of zeropotential, botfi wires of the telephonesystem being used in parallel on the telegraph-line and the oppositehalf of the line being formed by the ground. A circuit of this kind maybe successfully used, as the impedance of the telegraph instruments orof auxiliary resistance located in the short line wili prevent groundingof the telephone-circuit. Attempts have been made to utilize a similarsystem for multiplex telephony, a transmitter and a receiver taking theplace of the key and sounder and connected inductively to the main line.Attempts have also been made to establish phantom circuits by connectingtwo all-metallic telephone-circuits by a line bridging between thepoints of zeropotential on each and to which auxiliary telehone sets areinductively connected. So far as I am aware, however, these attemptshave not been successful from a practical standpoint, owing to lack ofbalance of the line, inasmuch as the electrical properties of theall-metallic circuit forming one leg of the superposed circuit woulddiffer from the elec- So far as Y trical properties of the all-metallictelephonecircuit forming the opposite leg. These differences are due inpart to differences in the length of the lines, to differences in theresistance, self-induction, or disturbance due to the passage ofcurrents of difference of character on adjacent lines to which eithercircuit may be inductively related.

One of the objects of the present invention is to provide a superposedor phantom circuit in which provision is made for gradually balancingthe lines-with reference to locals of the main circuit and establishinga zero-potential to form the point of connec tion with the bridging-wireforming the ph antom circuit.-

A still further object of the invention is to provide such an improvedbalancing means which may be gradually adjusted to accommodate varyingconditions.

Other objects and advantages will be fully explained in the followingdescription, and the invention will be more particularly pointed out inthe claims.

Reference is had to: the accompanying drawings, which form a part ofthis application and specificationf Figure 1. is a diagram of a telehone-circuit arranged in accordance with t e invention, illustrating asuperposed or phantom circuit formed by connecting two all-metallictelephone-circuits. Figs. 2 and 3 are similar views illustrating slightmodifications of the ways of wiring. Fig. 4 is a detail view of theadjustable balancing means. Fig. 5 is a similar illustration to thatshown in Fig. 1, but shows a multiple connection instead of the seriesconnection shown in Fig. 1. Fig. 6 illustrates a multiple connectionwith one movable spool for the balancing means.

Similar characters of reference are used to indicate the same partsthroughout the several views.

The apparatus will be described in detail, and then the differencesbetween the multiple and series connection will be pointed out and someof the advantages of the multiple connection explained.

In Fig. 1, A, B, O, and D designate four stations, at each of which is atransmitter 1, a battery 2, and an induction-coil 3, all of the usualconstruction and the primary of the coil being connected to the battery.The transmission is made in the ordinary manner.

The secondary 4 includes an ordinary form j necessary for the operationof the superposed of receiver 5 and is arranged in inductive relation tothe main line connecting the stations. .Between stations A andB extendmain lines 6 and 7, and between stations C and D extend main lines 8 9.The connection between each secondary and the main line is formed byinduction-coils or transformers 10, which may be of the ordinaryinduction-coils 11 is employed, said second set being of theconstruction best shown in Fig. 4. 20 designates a suitable support, onwhich are arranged two fixed spools 21 and 22 and two movable spools 23and 24 at each of the stations A, B, C, and D. The linewire "6 isconnected to the spool 21, and the line-wire '7 is connected to thespool 22. The windings of spools 21 and 22 extend in oppositedirections, so that one will counteract the effect of the other. Lines 8and 9 are connected at stations C and Din a similar manner. The coils2-3 and 24 are connected to the opposite sides of the secondary and areto be wound, respectively, in opposite directions, and these two coilsare adjusted independently of each otherto vary the distancebetween'them and the fixed coils at the ends of the support 20. Thereason for using the repeating-coils '10 is in order to increase theefiiciency of the apparatus, the balancing-coils 11 being more or lessseparated or dissociated from one another will not be as eflicient intransmitting as will the repeating-coils 10, which areintimatelyassociated. In some cases where efficiency is of minorimportance the repeating-coils may be dispensed with, as shown in Fig.2. The repeating-coils as herein used are such as are ordinarily used,the coils 11 being the coils which I employ for the purpose of obtainingthe balancing effect above noted and for preventing cross-talk betweenthe phantom circuit and the main circuit. Between the two main circuitsare phantom stations E and F, each including a transmitter 12, a battery13, and an induction-coil 14, and the secondary of said induction-coilbeing connected by a wire 15 to the two main metallic circuits at thepoints 16, and in order that conversation may be carried on betweenstations E and F without interfering with conversations between stationsA and B or between stations 0 and D the movable coils 23 and 24 at eachstation must be shifted oradjusted with ref erence to coils 21 and 22 ateach station until there is silence in the receivers of stations A and Band stations C and D. This may be said to be establishingzero-potentials at the point 16 and in the receivers of the stations A,B, C, and D. In this manner cross-con- ,versation or other disturbingnoises may be entirely eliminated between the stations E and F and thefour other stations. It must be understood that the movable coils arenot 1 l l i l l l l l or phantom circuits, but are used to prevent theinterference of the superposed or .phan' tom circuits with the main orassociated circuits and to prevent the main or associated circuits-frominterfering with the superposed or phantom circuits. If the point ofconnection 16 is exactly at zero-potential, conversa- 1 tion can becarried on through the phantom type, and in addition to these a secondset of circuit, and to obtain this balancing effect of the oppositesides of the lines transformers or induction-coils (illustrated in Fig.4) are employed. If there is less resistance on the wire 6 than on thewire'7, a stronger magnetic field will be created at the coil 21 than iscreated at the coil 22, and for this reason the coil 23 should beadjusted to a greater distance from'the coil 21 than coil 24 isseparated from the coil 22. This alters the inductive relation betweenthe main line and the secondary.

The arrangement of the circuits may be altered to suit varyingconditions, and in Fig. 2 is shown a system similar to that illustratedin Fig. 1, the auxiliary induction-coils 10 being omitted and a phantomcircuit and its telephones for stations being provided withinduction-coils 11 of the character shown in Fig. 1.

In Fig. 3 is illustrated a system in which three main lines 6, 7, and 9are employed to form two metallic telephonecircuits, this being accomplibed by connecting a third wire 9 into the two wires'6 and 7 ofanall-metallic c1rcuit, the two wires 6'and 7 of the all-metalliccircuit forming in parallel one-half ofthe second or superposed circuit.

Referring now to Fig. 1, the circuit between stations A and B is acomplete metallic circuit, and conversation. may be carried on in theusual manner. The circuit-connecting stations C and D is also a completemetallic circuit. In order that conversation may be carried on between.the phantom stations E and F without disturbing other stations, it isnecessary that the sides of the local circuits be balanced by properadjustment of the coils 23 and 24. The wires 15 are connected to themetallic circuits at points of zero-potential relative to the localstations of the mains, so that the wires 6 and 7 will be used inparallel as one conductor between phantom stations E and F. The twowires 8 and 9 will be used in parallel as the second or return conductorbetween stations E and F. This makes a complete metallic circuit between stations E and F, and the current entering the wires 6 and 7 or 8and. 9 will split and traverse both lines in the samedirection and againunite at the opposite end of this double conductor. When arranged inthis manner, it is found that conversation may be In carrying theinvention intopractice the I tween spool 35 and the primary ofrepeatingspools 21 and 22 may be fixedly secured to a suitable supportand spools 23 and 24 may be fitted snugly thereon, so that when adjustedthey will remain in position by virtue of friction against the support,or the coils .23 and 24 may be disposed in any suitable manner so thatthey can be adjusted relative to coils 21 and 22, respectively, or thespools 23 and 24 may be fixed and 21 and 22 may be movable. Therepeating-coil 1.0 has two primary and two secondary windings. will benoted that the adjustment of the coils permits the shifting of the pointof zero po tential through a considerable range,this being accomplishedby winding the primary and the secondary coils on separate spools, of

which one may be bodily moved toward and from the other to any desiredextent, while the support employed may be formed of wood or othernon-metallic material.

Figs. 5 and 6 illustrate my invention applied to multiple connections.In Fig. 5, A, B, O, and D designate four stations, at each of which is atransmitter 36, a battery 38, and a primary 46 and secondary 41. of aninduction-coil, all similar to the corresponding elements in Fig. 1. Thesecondary 41 includes a receiver 37, arranged as in Fig. 1. Betweenstations A and B extend main lines 30 and 31, and between stations C andI) extend main lines 47 and 48. The connection between each secondaryand the main line is formed by the repeating-coils 40 and in addition tothese a second set of induction-coils 49. 5O designates a support forthe fixed spools 32 and 33 and two movable spools 34 and 35. The line 30is connected to station A at a point 43 between coil 32 and thesecondary of repeating-coil 40, and line 31 is connected at a point 42between spool 33 and the secondary of repeating-co1l 40, thus allowingcurrents passing over line 30 to pass through the repeatingcoil 40 andthe fixed spools 32 and 33 of coils 49 in multiple, returning on line31. The el'lect of this operation on the local stations of the mains andof phantom stations E and F is similar to that described of the elementsshown in Fig. 1. The manner of wiring may be varied, and the number ofmovable induction-coils may be varied. In Fig. 6 is shown a stationprovided with a repeating-coil 51, line-wires 52 and 53, fixed coils orspools 54 and 55, and one movable coil 56, and a switchboard pair oflines similarin operation to the operations of lines 57 and 58 01 thelocal statio'ns shown in Fig. 5. The difference be tween the multipleconnection and. the series connection is that the switchboard pair inthe multiple is connected. as follows: Wire 58 is connected at a point43, which is a point between spool 34 and the primary of repeating-coil40, and wire 57 of secondary 41 is connected at a point 42, which is apoint be coil 40, which is commonly known as a multiple connection. Inthe series connection the phantom circuit goes through the fixed orrepeating coil 40 and the fixed. coils 32 and 33 of the induction-coils49. Another difference is that in the multiple connection the fixed orrepeating-coil 40 may be opened withoutopening the circuit of the inductioncoil 49, and vice versa, whereas in the series connection openingthe fixed or repeating coil 40 would open also the induction-coils 49.One advantage of using the multiple connection of these coils is thatthe phantom circuit does not have to pass through the fixed coil 40.Hence it is not necessary for the fixed coil 40 to be absolutely di'l'lerential. Another advantage is that much resistance is removed. from thepath of the phantom circuit. Another advantage is that the fixed orrepeating coil 40 does not react on the mov-- able coil 34 and 35thatis, the current generated in the secondaries of the fixed or repeatingcoil 40 does not have to pass through the movable coils 34 and 35, andtherefore has no reaction on the primary or the movable coil 34 and 35,and vice versa.

One of the advantages of this invention is that it is readily applicableto circuits already in use, and the number of circuits in any group ofcircuits can be doubled, less one, to a reasonable extent.

Various other changes than those noted above may be made withoutdeparting from my invention. For instance, either of the coils of eitherset may be movable with respect to the other two, and any means may beemployed to lessen or increase the effect of one coil upon the other ateither side of the circuit.

Having fully described my invention, what I claim as new, and desire tosecure by Letters Patent, is a 1. In a telephone system, main circuitsprovided with local circuits, phantom circuits connected to said maincircuits at points of approximately equal potential, and inductive meansfor causing silence in the receivers of said local circuits wherebycrossconversation and disturbances between said main circuits andphantom circuits are eliminated.

2. In a telephone system having main circuits provided with localcircuits, phantom circuits connected to said main circuits at points ofapproximately equal potential, and induction-coils composed of aplurality of windings operatively connected in said main and localcircuits and capable of adjustments from and toward each other wherebypoints of zero-potential may be located in said local circuits.

3. In a telephone system provided with main metallic circuits havinglocal circuits, superposed or phantom circuits in combination with saidmain metallic circuits, and adusting devices consisting ot coils movabletoward and from each other for preventing cross-induction between saidsuperposed or phantom circuits and the local circuits of said mainmetallic circuit-s.

4. In telephony, the combination. with all circuits, of local circuitsarranged in inductive relation to the metallic circuits, sets ofbalancing-coils wound on separate spools and disposed, two of each setbeing in the metallic and the others in the local circuits, the spoolsot the local circuits being adjustable with relation to the metalliccircuits, and phantom circuits connected to the metallic circuits atpoints of zero-potential.

5. In telepi'iony, local circuit having windings arranged in multiple,metallic mains l"-.aving windings also connected in multiole, tile coilsof one set of windings being bodily adjustable with respect to the coilsof the other set and serving to balance both sides of the localcircuits, and phantom circuits connected to the ma ns atpoints ofzeropotential.

6. A telephone system comprising metallic circuits provided withrepeating-coils, inductive coils composed of movable and fixed spoolsconnected to said repeating-coils, said movable spools being disposed ininductive relation to said fixed spools, locals including secondariesconnect ed to said movable spools,

and phantom circuits connected to said metallic circuits and providedwith local circuits.

7. Local stat-ions including secondaries, mains arranged in inductiverelation thereto, a support, fixed coils carried by the support andconnected with the mains, adjustable coils connected. in thesecondaries, and a phantom circuit connected to the mains at point 5 ofzero-potential.

8. In a telephone system having main metallic talking-circuits, andrepeating co'i ls therein at stations, of phantom talking'cir cuitsconnected to said main circuits, a coil interposed in each limb or sideof said main circuit, one or more coils inductively disposed withrelation to the latter coils and connected in the local talking-circuitsof said main circuits, and means for varying the inductive effect of oneof the said coils upon the other at either side of the main circuit,whereby high efliciency of the apparatus is maintained as well ascross-talk and disturbing noises between the main and phantom stationsprevented.

In testimony whereof I set my hand, in the presence of two witnesses,this 20th day of September, 1904.

THOMAS P. JORDAN.

Witnesses:

' A. L. JACKSON,

J. D. CRUTOHER.

